CI Life Leech ice witch is built around the passive Node Ghost Reaver and Chaos Inoculation. Ghost Reaver is a passive node which convert life leech from your HP to ES. Chaos Inoculation makes you immune to Chaos Damage.
This build will allow u to take damage like a boss and shred your enemies while staying on full energy shield at all times.

Pros
High DPS and freeze lock.
No need for HP or HP flasks.
Always at Full ES.
Good solo and party play.

With some testing of my own and feedback from others, I've added new selection of gems to be used with this build.

Added Lightning Dmg Gem (20% quality adds 20% shock duration + 10% chance to shock)
This gem can be replaced by the default Increased Crit Dmg gem from the guide. If you plan to use this gem then use Elemental Weakness when you curse mobs.

Pros:
Great for fighting mobs with Cold resist.
Applies shock when you land a crit which can stack 3x for a total of 120% Increased Dmg.
Very useful if you applied shock on mobs which will benefit the whole party.

Cons:
The added dmg can be very random.
Not effective when fighting mobs with lightning resist.
Has (140%) Mana Multiplier which is 10% more than Increased Crit Dmg (130%).
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Cold Penetration (20% qality gives 10% Cold Damage)
This gem can be replaced by the default Increased Crit Dmg gem from the guide. Use Frostbite if you solo.

Pros:
Recommend for people with low critical chance.
Fixed damage with no RNG involved. Flat reduction of 35% cold resist at lvl 20.
Very effective against mobs with cold resist.

Cons:
Not very effective if your curse can already drop the mobs to 0% resist.
It is harder to roll a 3 Green 1 Red and 2 Blue on a 6Link.
Has (150%) Mana Multiplier which is 20% more than Increased Crit Dmg (130%)
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Added Chaos Damage (20% quality adds 10% Chaos Damage)
This gem can be replaced by the default Increased Crit Dmg gem from the guide. Use Frostbite if you solo.

Pros:
Recommend for people with low critical chance.
Flat added dmg with very high rolls.
Alot of mobs does not have resistance to Chaos Dmg.
Does not reflect elemental dmg because Chaos isnt consider as elemental.
Is not affected by Elemental Equilibrium.

Cons:
Has (150%) Mana Multiplier which is 20% more than Increased Crit Dmg (130%)
Weak when fighting mobs that have Chaos resist.

Haste Aura
Haste aura gives us bonus cast spd and movement up to 14% Cast spd at lvl 20 and 7% movement (data from wiki) and that is without putting the Inner Force buff into account. This will help u achieve the 0.25 cast spd in a easier way. I recommend running this aura when you have 950+ Max Mana and if you have enough resistance.

Purity
Purity aura is one of the best aura in the game. It gives 5% Max resistance and over 30% all resistance at lvl 20 with the Inner Force passive Node. If you lack resistance in your gear then this is the right choice for you.

Dont let the 5% Max resistance fool you because of the small number,5% is actually a whole alot when you do the math. Your max resistance now becomes 80% instead of 75%. This is a big buff to your defence and just like the Haste, i recommend at least 950+ Max Mana to run this 3rd Aura.

How to get 950+ Mana without getting Max Mana Node?
For our passive tree, we avoid taking any extra max mana node to maximize our dps and ES.
The easiest way to get 950+ Mana is to get at least 3 piece of gear which gives u at least 50+ Max Mana. If you find this hard then you can sacrifice 1 skill point to grab the extra 8% Mana from the Templar tree.

Faster Casting 2x (Quality not needed but nice to have)Lesser Multiple Projectile 1x (Quality not needed but nice to have)Greater Multiple Projectile 1x (Quality not needed but nice to have)Reduced Mana 2x (Quality not needed)Freezing Pulse (Quality is a must for end game)Ice Spear (With quality good but not needed)Increased AOE (With quality good but not needed )Frostbite(With quality good)Temporal Chain (With quality good)Elemental Weakness (With quality good)Mana Leech (With quality very good)Life Leech (With quality very good , not needed if you go Vaal Impact)Summon Skeleton (Quality not needed)Minion Life (Quality not needed but good to have)Blood Rage (Optional gem not needed but good to have)Clarity (Quality not needed) Discipline (Quality not needed)Cold Penetration (Quality not needed)

Early game will be focus on the basic starting route for most CI built. A balanced offensive and defense with the preparation for mid and late end build.-------------------------------------------------------------------------------------------Mid Game

Mid game will be focus on getting more damage and ES which will be needed for the main end game build.--------------------------------------------------------------------------------------------
Now that we reached end game, there is a few routes that you can choose from.1. More Spell Damage
2. Vaal Pact route
3. Defensive route
4. 0.25 Cast Spd Freezing Pulse

Vaal Pact passive node allows Life Leech to be applied instantly.
You thought Life Leech was instantly applied? (Read below for a explanation)

Spoiler

The rate at which you gain life from life leech is 20% of maximum life per second. If you have 1000 maximum life, and leech 600 life with a single attack, it will take three seconds for that life to be applied to your current life. You always get the full amount of life leeched, although it may take time to be applied - if you leech a large amount of life during a battle, you may find that the life gain continues long after the battle is over.(credit taken from the Mechanics thread)

Curses
Frostbite and Temporal Chain should be your main curse spell for soloing. Frostbite is good against mobs with cold resist and Temporal Chain is good for mobs that uses flicker strike and works well on bosses. Elemental Weakness is for party play since it benefits from all types of element (except physical)

Main Auras
Clarity - Must get as soon as it becomes available.
Discipline - Get this when you have enough Mana pool to run both Aura

Early Game
At early levels you will be using freezing pulse(u can get from quest reward)to kill almost everything since its your main skill. Also get Ice spear which you will be using to snipe boss from a safe distance(not needed). You should have no trouble getting thru act 1 since its easy. Your next goal is to find a 4L gear piece (it can be anything as long as its 4L.

You will be using the following support gems: Faster casting + Lesser Multiple projectile + Faster Projectile + Freezing pulse (if you have a high quality freezing pulse then you can switch out the faster projectile for increased crit chance or dmg).

At level 31, you can use spell totem. Find another 4L piece and use the following gems:Faster Cast + Ice Spear + GMP + Spell Totem (if you cant afford a greater multiple projectile then get another lesser projectile in the meanwhile).

This Ice Spear totem can be set from behind or infront of you to provide extra damage and protection. You should be around mid game after finishing Normal.

Mid Game Cruel Difficulty

This is where the game gets a bit tough. Especially in Fetid Pool where the Rhoa can 2 hit you if your gear isnt good. From here on, i advise you get the summon skeleton gem + minion life linked to it and use it as a meat shield. Simply summon them and place your totem behind them and proceed to spam freezing pulse. This is extremely safe method to fight bosses like Brutus who pulls you in. Take advantage of your summons and let Brutus pull them in instead. (More info soon to come)

End Game
You should be preparing to grab CI and Ghost Reaver soon. I would advise you take CI when your energy shield is at least around 2500. To gain some fast levels, i advise joining team in Act III and farm docks (Note: CI is not needed to farm docks). Your main goal is to get 75% Fire Resistance when you farm dock because it will make those dog do alot less damage. If you have no fire resistance then you will get 1 hit by the rare Dog in docks. Farm docks to build up some currency and lvls to prepare for 5L chest.

When to take Ghost Reaver?
Ghost reaver should only be taken when you purchase a 5L chest. The following gems is needed to make this possible: Mana Leech + Life Leech + Faster Casting + LMP + Freezing pulse. After you achieve this then you should have no Mana problems. However, it is possible to use Ghost Reaver with 4L but its not advised b/c you will be having some serious mana issues.

End Game MAPS
This is what the build is really for. You have the option to solo or group, both works well with this build. I recommend at least 3000+ ES before you start doing maps. Why 3000+ ES? Because monster in maps hit like a truck and dying is a harsh penalty(15% exp lost and Game Over for HC). I recommend at least 4000 ES if you plan to use this build on Hardcore and i advise HC players to take the more defensive route.

Capping Resistance
This should not be a hard factor if you invest a bit into. Merciless is a -60% to all resistance but our passive tree gives us a 40% all resistance, thus making it -20%.
End Game maps mob are randomly generated and consists of mob that uses all sort of elemental damage so if you cant cap the resistance then you should at least have +50% to all resistance. Belt with 2 resistance should be easy to get and also prismatic rings are also a good way to get more resistance.

Life Leech
Your Life Leech comes from the support gem. Gears that has the mod that says +% Phy Dmg to life Leech DOES NOT apply to this build. Freezing pulse is a spell so those mods are useless to us.

Since we're CI, we dont need to use any HP flask.
We will be running 2 Mana Potion + Granite Flask + 2 Quicksilver, view my current gears on what MODS to roll on them. Dispel Frozen and Chilled is important and should have at least 2 flask with that mod. One of mana flask and another on quicksilver which allows quick escape incase of frozen.

Read if you have 6L chest

Spoiler

6L chest is a major improvement from 5L since now have the option for a extra DMG support gem.

In order to achieve 0.25 Sec , you will need a total of 150% Increased Cast Spd.
The image below shows that it is possible with Bloodrage.Bloodrage can give up to 15% cast spd and with the Inner Force Passive , it has a duration of 10 second which refreshes everytime u kill a mob. The animation is extremely fast and makes u feel like a Machine Gun. I will try to put up a video later on to show animation.

I have a total of 7k ES while running dual wand for extra power or 9k ES with shield. It is recommended that you use a shield unless you have enough ES to dual wand. With this build, im soloing all maps without any problem.
I dont need to run away from any close ranged mob since i have life leech. If i get surrounded by alot, i can use a granite flask and hold my ground. Overall its a nice build to play and farm with no risk of dying once you get the hang of it.

Note:This technique will not work if you have taken CI. This easy and inexpensive 100% increased item find will not work in dark caves also. This is because of how the game is designed. When ur low on life, your vision is decreased dramatically making it hard to see any target from afar.

Haste should be linked to Blood magic while wearing the Unique Boots.

The Ledge
The ledge is a great place to farm as a solo or party. If you used the requirement gear and gem listed then you should have a free 100 Increased Rarity find and on top of an extra aura which increases your cast spd and movement. Haste should be lvled to your dex cap. I advise running GMP + Mana Leech + Fast cast + Freezing Pulse + Item Rarity or Quantity if u have a 5L.

Why use GMP?
The ledge has alot of mobs stacked together so using GMP gives u a much bigger range to clear faster.

FellShrine Ruins
Same rules apply here but when your low on life, the place gets alot darker and might be an issue for some ppl.Docks
This is one of my favorite place. To farm here , you will need to get fire resistance to Cap and use the same setup as Ledge.

A few bones to pick on your build... I don't know why you would want quality on your life leech gem if you're getting vaal pact anyway... Quality on life leech only improves the life leech rate of the linked spell => The life leech regen cap at 20% of your max hp/ES is increased. Vaal pact makes quality on life leech obsolete...

Another nitpick is lack of auras in your build. No matter what character you play, you want to run at least 2 auras. Not mentionning discipline in a CI build seems kinda weird...

A few bones to pick on your build... I don't know why you would want quality on your life leech gem if you're getting vaal pact anyway... Quality on life leech only improves the life leech rate of the linked spell => The life leech regen cap at 20% of your max hp/ES is increased. Vaal pact makes quality on life leech obsolete...

Another nitpick is lack of auras in your build. No matter what character you play, you want to run at least 2 auras. Not mentionning discipline in a CI build seems kinda weird...

2. I'll shoot my spell totem down to permafreeze EVERYTHING and spam Ice Spear to permafreeze EVERYTHING things coming from different directions (or if you're in a party that already has DPS and doesn't need your FP).

Why I don't use dual totems.

Spoiler

You can act as a totem yourself and shoot ice spears + freezing pulse and you don't be deducted that 50% damage. You can aim where you want your spells to go instead of two totems shooting at the nearest things. You get ES leech for better survivability.

2. I'll shoot my spell totem down and spam Ice Spear to freeze things coming from different directions (or if you're in a party that already has DPS and doesn't need your FP).

Why I don't use dual totems.

Spoiler

You can act as a totem yourself and shoot ice spears + freezing pulse and you don't be deducted that 50% damage. You can aim where you want your spells to go instead of two totems shooting at the nearest things. You get ES leech for better survivability.

Great guide btw!

Thx for commenting
But the support gem u mention for freezing pulse would require 98 mana per shot using a lvl 18 Freezing pulse gem. With a cast spd of 0.32 on fp = 98x3 Mana = 294 per Sec.
There is no way you will have enough mana to keep using FP if you use those support gems unless with mana leech.

Also Faster Projectile is a waste of a slot when you get a high quality freezing pulse.

Items like this with some mana regen nodes will allow me to spam freezing pulse as I wish. It does go down, albeit very slowly, but if I stop shooting for even a split second I'll get enough mana to spam yet again. Also nothing an instantaneous mana pot can't solve. Faster projectile (even with quality FP, and I have both quality so I cover a LARGE area) helps because it does more projectile damage. However, depending on the route you go on your build you may switch it out for something else like Added Cold Damage or Added Lightning Damage.

Items like this with some mana regen nodes will allow me to spam freezing pulse as I wish. It does go down, albeit very slowly, but if I stop shooting for even a split second I'll get enough mana to spam yet again. Also nothing an instantaneous mana pot can't solve. Faster projectile (even with quality FP, and I have both quality so I cover a LARGE area) helps because it does more projectile damage. However, depending on the route you go on your build you may switch it out for something else like Added Cold Damage or Added Lightning Damage.

This guide uses the Unique necklace and you can see that we didnt take any mana regen nodes also expect the 40% and the 20% from the big node on the templar tree.

I have alrdy tested in the past even with Mana leech on, using GMP with additional more dmg support gem is not enough. Its fine if you hit a big wave mobs but single or 2 target is not enough and its bad for killing bosses.